1. Field of the Invention
The present invention refers to a synchronizer sleeve for a change speed gear, which comprises a shift fork recess opening towards the outer peripheral surface of the synchronizer sleeve, and a tooth means formed at its inner peripheral surface.
2. Brief Description of the Prior Art
Synchronizer sleeves of this type are used in manual change speed gears. Then the synchronizer sleeve comprises at least one pressure surface which is regularly hardened and formed at the front end side of the synchronizer sleeve and which cooperates with a synchronizing ring for the frictional synchronization of the rotational speed. If synchronizer sleeves are used in electrically shifting gears in which the synchronization is carried out electronically, the formation of such a pressure surface at the front end side of the synchronizer sleeve can be renounced.
Synchronizer sleeves are usually manufactured from a blank generated by means of shaping, preferably by forging, said blank being fully turned on the lathe to manufacture the final contour of the ready synchronizer sleeve. On the inner peripheral surface of the synchronizer sleeve, a gear tooth arrangement is then broached or shaped in a conventional manner. Undercuts of this toothing are usually manufactured by rolling. Then details are milled. The component manufactured in this manner is then carburized.
In a manufacturing method of this type a certain surface hardness determined by the carburizing or nitriding process results on the entire component.
The carburizing of the synchronizer sleeve on the one hand involves the disadvantage that the component finished in its final contour must run through a relatively long hardening process. Moreover, a casting at the component may occur during the carburizing process so that the dimensional accuracy of the synchronizer sleeve is affected. Due to the instrumental and timely effort, the carburizing process is relatively expensive.
The object of the present invention is to provide a synchronizer sleeve, which without affecting the resistance to wear of the component, can be manufactured in a more inexpensive way. The object of the invention is furthermore to provide a method for the inexpensive manufacture of a synchronizer sleeve.
To solve this object, the synchronizer sleeve of the above-mentioned type is developed by the present invention in that the surface hardness of the shift fork recess is set by work-hardening, and that the tooth arrangement is locally hardened, in particular inductively hardened.